scholarly journals Moisture Performance of Façade Elements Made of Thermally Modified Norway Spruce Wood

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 348 ◽  
Author(s):  
Miha Humar ◽  
Boštjan Lesar ◽  
Davor Kržišnik
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Norway Spruce ◽  
Spruce Wood ◽  
Moisture Performance ◽  
Average Relative Humidity ◽  
Thermally Modified Wood ◽  
Moisture Content Measurement ◽  
Modified Wood

Wooden façades are gaining in importance. Thermally modified wood is becoming one of the preferred materials for claddings. In spite of the fact that façades made of thermally modified wood have been in use for more than two decades, reports about long-term monitoring have been sparse. The results of three-year monitoring of a façade made of thermally modified wood in Ljubljana are reported. Moisture content measurements of thermally modified façades were taken at 22 locations and compared to the moisture content of untreated Norway spruce wood. Temperature and relative humidity were recorded in parallel. The moisture content of the wood was compared to the average relative humidity before the measurements. The results confirm the lower moisture content of thermally modified wood in comparison to reference Norway spruce. The moisture content of the wooden façade could be best correlated with the average relative humidity and temperature 48 h before the wood moisture content measurement was taken.

scholarly journals Karakteristik Pengeringan Biji Jagung (Zea Mays L.) Menggunakan Alat Pengering Surya Adriyarkara Termodifikasi

2018 ◽  
Vol 3 (2) ◽  
pp. 351-360
Author(s):  
Athul Fadhli ◽  
Diswandi Nurba ◽  
Raida Agustina
Keyword(s):  
Zea Mays ◽  
Relative Humidity ◽  
Moisture Content ◽  
Zea Mays L ◽  
Initial Moisture Content ◽  
Solar Irradiation ◽  
Air Velocity ◽  
Drying Time ◽  
Average Temperature ◽  
Average Relative Humidity

Abstrak. Jagung merupakan tanaman penghasil karbohidrat terpenting. Pengeringan jagung pipil menggunakan alat pengering merupakan proses untuk menghasilkan jagung pipil yang siap diolah untuk pembuatan tepung jagung dengan batas kadar air tertentu sehingga menghaslkan jagung pipil dengan kualitas yang baik. Tujuan penelitian ini adalah untuk mengkaji karakteristik pengeringan biji jagung menggunakan alat pengering surya Termodifikasi. Metode penelitian  menggunakan 3,15 kilogram jagung pipil dengan kadar air awal 22% untuk proses pengeringan. Parameter yang dianalisis terkait alat pengering kolektor surya yaitu temperatur, kelembaban relatif, kecepatan udara dan iradiasi surya, sedangkan parameter yang dianalisis terkait bahan yaitu kadar air, lama waktu pengeringan, laju pengeringan dan organoleptik. Prosedur penelitian terdiri dari pengujian kosong dan pengujian dengan menggunakan jagung pipil. Hasil penelitian menunjukkan bahwa temperatur rata-rata dalam rak pengering sebelum dilakukan modifikasi yaitu 44,4oC, temperatur rata-rata setelah dilakukan modifikasi yaitu 55,5oC dan temperatur rata-rata rak pengering pada pengeringan menggunakan jagung pipil yaitu 46,96oC. Kelembaban relatif rata-rata dalam rak pengering sebelum dilakukan modifikasi yaitu 40,1%, kelembaban relatif rata-rata dalam rak pengering setelah modifikasi yaitu 35,1% dan kelembaban relatif rata-rata pengeringan menggunakan jagung pipil yaitu 44,45%. Dari hasil pengukuran tersebut menunjukkan bahwa nilai temperatur dan kelembaban pada alat setelah modifikasi lebih baik dibandingkan sebelum alat dimodifikasi. Pengukuran temperatur dan kelembaban relatif terdiri dari 4 titik pengukuran yaitu rak 1A,1B dan rak 2A, 2B. Kecepatan udara rata-rata yang diukur konstan yaitu 0,7 m/s pada ruang pengering, sedangkan lingkungan 1,1 m/s. Total iradiasi surya selama pengeringan yaitu 1848,84 W/m2. Kadar air jagung pipil masing-masing rak yaitu rak 1A 14,29%, rak 1B 14,47%, rak 2A 13,91% dan rak 2B 14,1%. Hasil dari pengujian organoleptik, panelis agak menyukai jagung pipil yang dikeringkan menggunakan alat pengering tersebut.Characteristics of Seed Drying (Zea mays L.) Using a Modified Adriyarkara Solar DryerAbstract. Corn is the most important carbohydrate plant. Drying corn using a drying tool is a process to produce corn that are ready to be processed for making corn flour with a certain water content limit so as to produce corn with good quality. The purpose of this study was to examine the characteristics of drying of corn kernels using a modified solar dryer. The research method used 3,15 kilogram of corn milled with the initial moisture content of 22% for drying process. The parameters analyzed in relation to solar collector dryers are temperature, relative humidity, air velocity and solar irradiation, while the parameters analyzed are materials such as moisture content, drying time, drying rate and organoleptic. The research procedure consists of unloaded testing and testing using corn. The results showed that the average temperature in the dryer tray before modification was 44,4°C, the average temperature after modification was 55,5°C and the average temperature of the dryer tray on drying using corn was 46,96oC. The average relative humidity in the dryer tray before modification is 40,1%, the average relative humidity in the dryer tray after modification is 35,1% and the average relative humidity of drying using corn is 44,45%. From the measurement results show that the value of temperature and humidity in the tool after modification is better than before. Measurement of temperature and relative humidity consist of 4 point of measurement that is tray 1A, 1B and tray 2A, 2B. Average mean air velocity measured is 0,7 m/s at the dryer room, while the environment is 1,1 m/s. Total solar irradiation during drying is 1848,84 W/m2. Moisture level of corn each shelves tray 1A is 14,29%, tray 1B is 14.47%, tray 2A is 13,91% and tray 2B is 14,1%. As a result of organoleptic testing, panelists rather like dried corn using the dryer.

scholarly journals Effects of Variable Humidity on the Creep Behavior of Concrete and the Long-Term Deflection of RC Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Pengfei Li ◽  
Shiqin He
Keyword(s):  
Experimental Data ◽  
Relative Humidity ◽  
Creep Strain ◽  
Analytical Models ◽  
Deformation Characteristics ◽  
Rc Beams ◽  
Test Results ◽  
Sustained Loads ◽  
Average Relative Humidity

The influences of variable humidity on the creep behaviors of concrete and the long-term deflections of RC beams are analyzed in this paper. A total of 6 prismatic specimens and 5 RC beams were subjected to sustained loads and 3 types of variable humidity conditions for 331 days. The creep strains of the prismatic specimens and the deflections of the RC beams were recorded to investigate the long-term deformation characteristics. The test results reveal that both the creep strain and the deflection of specimens under cyclic humidity conditions exhibit approximately linear tendencies that are obviously less than those of specimens exposed only to natural air. During certain wetting cycles, the deformation rate became slower and the creep strain even recovered with an increase in the humidity, especially for shorter wetting-drying cycles. Long-term deflections predicted using the CEB-FIP 90 and ACI 209R models were compared with the test results to evaluate the versatility of these current specifications. The findings included rather large errors between the predicted results and experimental data when the average relative humidity was adopted in the analytical models.

scholarly journals Occupational Exposure to Dust Produced when Milling Thermally Modified Wood

2020 ◽  
Vol 17 (5) ◽  
pp. 1478 ◽  
Author(s):  
Alena Očkajová ◽  
Martin Kučerka ◽  
Richard Kminiak ◽  
Ľuboš Krišťák ◽  
Rastislav Igaz ◽  
...  
Keyword(s):  
Feed Rate ◽  
Dust Particles ◽  
Wood Dust ◽  
International Agency ◽  
Oak Wood ◽  
Granular Composition ◽  
Spruce Wood ◽  
Thermally Modified Wood ◽  
Unmodified Wood ◽  
Modified Wood

During production, thermally modified wood is processed using the same machining operations as unmodified wood. Machining wood is always accompanied with the creation of dust particles. The smaller they become, the more hazardous they are. Employees are exposed to a greater health hazard when machining thermally modified wood because a considerable amount of fine dust is produced under the same processing conditions than in the case of unmodified wood. The International Agency for Research on Cancer (IARC) states that wood dust causes cancer of the nasal cavity and paranasal sinuses and of the nasopharynx. Wood dust is also associated with toxic effects, irritation of the eyes, nose and throat, dermatitis, and respiratory system effects which include decreased lung capacity, chronic obstructive pulmonary disease, asthma and allergic reactions. In our research, granular composition of particles resulting from the process of longitudinal milling of heat-treated oak and spruce wood under variable conditions (i.e., the temperature of modification of 160, 180, 200 and 220 °C and feed rate of 6, 10 and 15 m.min−1) are presented in the paper. Sieve analysis was used to determine the granular composition of particles. An increase in fine particle fraction when the temperature of modification rises was confirmed by the research. This can be due to the lower strength of thermally modified wood. Moreover, a different effect of the temperature modification on granularity due to the tree species was observed. In the case of oak wood, changes occurred at a temperature of 160 °C and in the case of spruce wood, changes occurred at the temperatures of 200 and 220 °C. At the temperatures of modification of 200 and 220 °C, the dust fraction (i.e., that occurred in the mesh sieves, particles with the size ≤ 0.08 mm) ranged from 2.99% (oak wood, feed rate of 10 m.min−1) to 8.07% (spruce wood, feed rate of 6 m.min−1). Such particles might have a harmful effect on employee health in wood-processing facilities.

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Lisbeth G. Thygesen ◽  
Emil Tang Engelund ◽  
Preben Hoffmeyer
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Norway Spruce ◽  
Water Sorption ◽  
Capillary Condensation ◽  
Theoretical Contribution ◽  
Low Field ◽  
Condensed Water ◽  
Relaxation Curves ◽  
Curve Form

Abstract Desorption isotherms at 20°C for untreated, acetylated, and furfurylated Norway spruce [Picea abies (L.) Karst.] sapwood were established in the 91.9–99.9% relative humidity (RH) range. Three methods were employed to secure various constant RH levels: saturated salt solutions, climate chambers, and the pressure plate technique. The curve form for the untreated samples did not show an upward bend, except perhaps above 99.5% RH, indicating that – contrary to what has hitherto been assumed – capillary condensation does not play a significant role for water sorption in wood below fiber saturation. Three additional results corroborate this conclusion: (1) calculation of the theoretical contribution of capillary condensation to the moisture content (MC) in wood based on idealized microstructural geometries by means of the Kelvin and Laplace equations resulted in very small contributions to the equilibrium moisture content (EMC), i.e., below 0.35% moisture at 99.9% RH. (2) The ratio between the EMC of acetylated and untreated samples did not show an increasing trend for increasing RH, as would have been the case if capillary condensation had taken place in both untreated and acetylated wood. (3) Low field time domain nuclear magnetic resonance results showed that only the relaxation curves from the furfurylated samples were affected systematically by freezing, indicating that neither untreated nor acetylated wood contained significant amounts of capillary condensed water.

scholarly journals Moisture content changes of beech and ash elements during two years in room conditions

2021 ◽  
pp. 97-110
Author(s):  
Goran Milic
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Air Conditioning ◽  
Cold Winter ◽  
The Past ◽  
Average Relative Humidity ◽  
The Subject ◽  
Sawn Timber

The subject of this paper is the analysis of moisture content (MC) changes of beech and ash wood during two years in room conditions (heating during winter; no air conditioning during summer). The registered MC changes are primarily the result of changes in relative humidity of the air (measured by capacitive probes). The average relative humidity of the air in the interior is lower today than in the past, as also shown in this experiment (the average relative humidity of air during two years was 44%). The lowest wood MC was reached on very cold winter days when the heating was on even during the night - between 5% and 6%, and the highest one at the beginning of June: 10.4-10.9%. As expected, the wood did not reach equilibrium moisture content - during winter, MC is by about 1% higher, and in summer it is lower by up to 2.5% than the equilibrium. The recommendation that the sawn timber from which the interior products will be made should be dried at 7-8% MC was confirmed.

scholarly journals Storage Temperature and Moisture Content Affect Respiration and Survival of Ranunculus asiaticus Dry Tuberous Roots

HortScience ◽  
2011 ◽  
Vol 46 (11) ◽  
pp. 1523-1527 ◽  
Author(s):  
Christopher B. Cerveny ◽  
William B. Miller ◽  
Alan G. Taylor
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Storage Temperature ◽  
Glycerol Water ◽  
Water Solutions ◽  
Tuberous Roots ◽  
Ranunculus Asiaticus ◽  
Flow Through ◽  
Closed Systems

Ranunculus asiaticus (L.) is an ornamental geophyte with some commercial production challenges presumed to be related to the storage of its desiccation tolerant tuberous roots (TRs). We investigated the influence of temperature and relative humidity during storage on viability of R. asiaticus TRs. The TRs were stored in specialized chambers for controlling relative humidity under flow-through or closed systems. In the flow-through system, air was bubbled through glycerol–water solutions to create relative humidities of 20%, 40%, 60%, 80%, or 100% and then passed through storage chambers held at 5, 20, or 35 °C for up to 20 weeks. In closed storage, tissue was equilibrated to a given moisture content (fresh basis) at 15 °C by suspending TRs over glycerol–water solutions (35%, 60%, or 85% relative humidity) with fans to circulate air. These containers were closed for 4 weeks and then tissue was transferred to sealed jars for up to 17 weeks at 5 or 25 °C. In both systems, TRs held with elevated temperature and relative humidity had the largest decrease in percent survival when planted after storage. Flow-through storage gave greater variability in TRs moisture content than closed storage. Tuberous roots at 25 °C had higher respiration rates than at 5 °C under closed storage; elevated moisture content also led to increased respiration. From these results it can be concluded that R. asiaticus dry TRs should be stored cool and dry for long-term viability.

Fungal Degradation of Wood Plastic Composites Made with Thermally Modified Wood Residues

2016 ◽  
Vol 721 ◽  
pp. 8-12 ◽  
Author(s):  
Edgars Kuka ◽  
Dace Cirule ◽  
Janis Kajaks ◽  
Anna Janberga ◽  
Ingeborga Andersone ◽  
...  
Keyword(s):  
Wood Fiber ◽  
Fungal Growth ◽  
Fungal Resistance ◽  
Wood Fibers ◽  
Wood Plastic Composites ◽  
Fungal Degradation ◽  
Plastic Composites ◽  
Thermally Modified Wood ◽  
Modified Wood

Wood plastic composites (WPC) are mainly used as an outdoor material, so durability against fungal decay is one of the factors that should be analyzed and if necessary improved. WPC are susceptible to biodegradation, although these materials have limited water absorption because of the wood fiber encapsulation in polymer matrix. In the study two different water pretreatment methods (short-term and long-term) were used to ensure appropriate water content for fungal growth. Also in the paper thermally modified wood (different regimes) fiber influence on WPC fungal resistance is investigated. The results showed that long-term water pretreated WPC specimens had more suitable conditions for fungal degradation that led to higher weight loss. The results which were related to thermally modified wood fibers showed, that WPC with thermally modified wood fibers had improved resistance against fungi. Thermal modification regimes had an effect on WPC durability as well.

scholarly journals The First Evidence of the Insecticidal Potential of Plant Powders from Invasive Alien Plants against Rice Weevil under Laboratory Conditions

2020 ◽  
Vol 10 (21) ◽  
pp. 7828 ◽  
Author(s):  
Tanja Bohinc ◽  
Aleksander Horvat ◽  
Miha Ocvirk ◽  
Iztok Jože Košir ◽  
Ksenija Rutnik ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Norway Spruce ◽  
Invasive Plants ◽  
Diatomaceous Earth ◽  
Wood Ash ◽  
Alien Plants ◽  
Rice Weevil ◽  
Invasive Alien Plants ◽  
Spruce Wood ◽  
Insecticidal Efficacy

In a laboratory experiment, we studied the insecticidal effects of invasive alien plants on the rice weevil. The research was carried out in two parts. In the first part, we studied the insecticidal properties of seven different plant species, namely, Bohemian knotweed (Fallopia × bohemica), Japanese knotweed (Fallopia japonica), false indigo-bush (Amorpha fruticosa), tree of heaven (Ailanthus altissima), staghorn sumac (Rhus typhina), Canada goldenrod (Solidago canadensis), and giant goldenrod (Solidago gigantea). Mixtures of powders and wheat were prepared in two different concentrations, namely, 2.5 w% and 1.25 w%. The experiment was performed at temperatures 20 °C and 25 °C and at two humidity levels, 55% R.h. and 75% R.h. Very low mortality (below 8%) was found when using combinations with the higher relative humidity. No significant differences were observed between the effects of these concentrations. In the second part of the experiment, Norway spruce wood ash and diatomaceous earth (product SilicoSec®) were added to the powder obtained by milling leaves of four different invasive plant species (Canada goldenrod, staghorn sumac, tree of heaven, false indigo). In the independent application, wheat was added to the powder at a concentration 2.5 w%. In the treatments that involved mixtures of powder and wood ash/diatomaceous earth, we applied 1.25 w% plant powder and 1.25 w% wood ash or 1.25 w% plant powder and 450 ppm of a SilicoSec® preparation. The positive control was carried out as two separate treatments with 2.5 w% wood ash of Norway spruce and 900 ppm of the SilicoSec® product, while untreated wheat represented the negative control. The experiment was performed at two temperatures (20 °C and 25 °C) and two R.h. values (55 and 75% R.h.). The mortality of beetles was recorded on the 7th, 14th, and 21st day after the start of the experiment. Higher mortality rates of rice weevil adults were found at the higher relative humidity, and an important factor of mortality was also the day of exposure, as a higher mortality was found when the exposure of individuals to the tested substances was for a longer time period. After 21 days at 25 °C and 55% R.h., the combinations in which the lower concentration of Norway spruce wood ash was added to the powder of invasive alien plants achieved more than 90% mortality of beetles. By adding the plant powder of invasive alien plants to wood ash, we achieved a greater insecticidal efficacy of invasive plants and lower concentrations of wood ash. Nevertheless, the results of our research do not indicate any great usefulness of the plant powder of invasive plants in suppressing the rice weevil. Additional studies should primarily focus on the insecticidal efficacy of powder from the genus Solidago, which in our study, displayed the greatest insecticidal potential among the tested invasive plants.

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